The influence of large- and small-scale magnetohydrodynamic (MHD) modes on plasma transport properties has been studied. Poloidal and toroidal reconstruction of large m = 2 modes and their evolution in time have been analysed, as well as their electron temperature profiles and heat transport properties with respect to the background plasma. The confinement is improved within the magnetic island, compared to the background plasma as evidenced by a secondary temperature maximum at the centre of the island. The perpendicular heat diffusivity inside the island is estimated to be of the order of 0.01 m2 s−1, which is close to the neoclassical value. By cross-correlation of different electron cyclotron emission (ECE) channels, temperature fluctuations in the presence of MHD modes are investigated. For m = 2 islands, they are found to be different for the X- and the O-points. Evidence of a small mode with higher m number between the q = 1 and 2 radii is given.
Recent results from the Large Helical Device